I have a decent workbench now but it’s too light for planing and chiseling so I want to build one for the job;
the workbench I need to build would be a heavier one,and woodworking vise.How small is too small for a planing,chiseling bench?I have very limited room and In a wheelchair would a 4’ one be heavy and stable enough?tail vise the best choice since I’m not planing to go large objects.I’m thinking a Paul sellers 2×4 style.

My bench is short, narrow, high and light (spruce and Douglas Fir), but it’s immobile like a stone boulder unless I’m doing heavy planing on a big board, at which the whole bench as a unit will move. No problem even then, I just anchor it with one foot.

The secret is to have a tight design with zero racking, and to have trestle and “feet” in the usual European style. Or splayed trestle legs, which I think is how the Paul Sellers design works.

-- Lao Ma: You are so full of anger and hatred. Xena: Everybody's gotta be full of something.

Go over the to “workbench smack down” thread. I’m just finishing up my Roubo style bench and I got a lot of help from the guys that hang out in that thread.If I can give my 2c worth, I’d suggest getting wider boards and rip them to size rather than going with the 2×4. you’ll find that a 2×10 or 2×12 are typically clearer and straighter than the smaller stuff. I picked through all the 16 footers and ended up getting a couple of 2×10x8 and these seem to be even better, they just didn’t have a enough for my complete bench.Whatever you decide, get enough for complete bench and sticker it in your shop for a few weeks to dry some more and more importantly acclimate to your shop.

I bought my 2’ x 4’ pine bench on Craigslist for $20 (no kidding) and added a few features: a mobile wheel mechanism, a heavy load bearing storage shelf, and a quick release vise that (on sale at Peachtree for $35), dog holes, etc. Yes I am Scottish :)
I might add an end vise next.
I put 3 sakrete (concrete) bags on the shelf (not in the photo) and, as a result, the bench is rock solid. I make reproduction furniture and do a lot of planing and the bench does not move. I did the same thing at my lathe. My point is that the bench itself does not need to be super heavy to be immobile.

Would accessing the bench on a wheelchair with a trestle base present a problem? A Roubo style bench with its apron would seem like it would not work. I’ve seen benches like this one that might give you the best access?

If you make a heavy top (4” thick) for a four foot bench should give you sufficient heft for planing and hand tools. I know Chris Schwartz wrote an article re wheelchair accessible benches. Let us know what you come up with. Tom